/*
   * Copyright (C) 2015, Wang Nan <wangnan0@huawei.com>
   * Copyright (C) 2015, Huawei Inc.
   */

  #include <errno.h>

  #include <limits.h>

  #include <stdio.h>

  #include <stdlib.h>

  #include <linux/err.h>

  #include "debug.h"
  #include "llvm-utils.h"

  #include "config.h"

  #include "util.h"

  #include <sys/wait.h>

  
  #define CLANG_BPF_CMD_DEFAULT_TEMPLATE				\

  		"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\

  		"-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE "	\

  		"$CLANG_OPTIONS $KERNEL_INC_OPTIONS "		\
  		"-Wno-unused-value -Wno-pointer-sign "		\
  		"-working-directory $WORKING_DIR "		\
  		"-c \"$CLANG_SOURCE\" -target bpf -O2 -o -"

  
  struct llvm_param llvm_param = {
  	.clang_path = "clang",
  	.clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
  	.clang_opt = NULL,
  	.kbuild_dir = NULL,
  	.kbuild_opts = NULL,

  	.user_set_param = false,

  };
  
  int perf_llvm_config(const char *var, const char *value)
  {
  	if (prefixcmp(var, "llvm."))
  		return 0;
  	var += sizeof("llvm.") - 1;
  
  	if (!strcmp(var, "clang-path"))
  		llvm_param.clang_path = strdup(value);
  	else if (!strcmp(var, "clang-bpf-cmd-template"))
  		llvm_param.clang_bpf_cmd_template = strdup(value);
  	else if (!strcmp(var, "clang-opt"))
  		llvm_param.clang_opt = strdup(value);
  	else if (!strcmp(var, "kbuild-dir"))
  		llvm_param.kbuild_dir = strdup(value);
  	else if (!strcmp(var, "kbuild-opts"))
  		llvm_param.kbuild_opts = strdup(value);

  	else if (!strcmp(var, "dump-obj"))
  		llvm_param.dump_obj = !!perf_config_bool(var, value);

  	else {
  		pr_debug("Invalid LLVM config option: %s
  ", value);

  		return -1;

  	}

  	llvm_param.user_set_param = true;

  	return 0;
  }

  
  static int
  search_program(const char *def, const char *name,
  	       char *output)
  {
  	char *env, *path, *tmp = NULL;
  	char buf[PATH_MAX];
  	int ret;
  
  	output[0] = '\0';
  	if (def && def[0] != '\0') {
  		if (def[0] == '/') {
  			if (access(def, F_OK) == 0) {
  				strlcpy(output, def, PATH_MAX);
  				return 0;
  			}
  		} else if (def[0] != '\0')
  			name = def;
  	}
  
  	env = getenv("PATH");
  	if (!env)
  		return -1;
  	env = strdup(env);
  	if (!env)
  		return -1;
  
  	ret = -ENOENT;
  	path = strtok_r(env, ":",  &tmp);
  	while (path) {
  		scnprintf(buf, sizeof(buf), "%s/%s", path, name);
  		if (access(buf, F_OK) == 0) {
  			strlcpy(output, buf, PATH_MAX);
  			ret = 0;
  			break;
  		}
  		path = strtok_r(NULL, ":", &tmp);
  	}
  
  	free(env);
  	return ret;
  }
  
  #define READ_SIZE	4096
  static int
  read_from_pipe(const char *cmd, void **p_buf, size_t *p_read_sz)
  {
  	int err = 0;
  	void *buf = NULL;
  	FILE *file = NULL;
  	size_t read_sz = 0, buf_sz = 0;

  	char serr[STRERR_BUFSIZE];

  
  	file = popen(cmd, "r");
  	if (!file) {
  		pr_err("ERROR: unable to popen cmd: %s
  ",

  		       str_error_r(errno, serr, sizeof(serr)));

  		return -EINVAL;
  	}
  
  	while (!feof(file) && !ferror(file)) {
  		/*
  		 * Make buf_sz always have obe byte extra space so we
  		 * can put '\0' there.
  		 */
  		if (buf_sz - read_sz < READ_SIZE + 1) {
  			void *new_buf;
  
  			buf_sz = read_sz + READ_SIZE + 1;
  			new_buf = realloc(buf, buf_sz);
  
  			if (!new_buf) {
  				pr_err("ERROR: failed to realloc memory
  ");
  				err = -ENOMEM;
  				goto errout;
  			}
  
  			buf = new_buf;
  		}
  		read_sz += fread(buf + read_sz, 1, READ_SIZE, file);
  	}
  
  	if (buf_sz - read_sz < 1) {
  		pr_err("ERROR: internal error
  ");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	if (ferror(file)) {
  		pr_err("ERROR: error occurred when reading from pipe: %s
  ",

  		       str_error_r(errno, serr, sizeof(serr)));

  		err = -EIO;
  		goto errout;
  	}
  
  	err = WEXITSTATUS(pclose(file));
  	file = NULL;
  	if (err) {
  		err = -EINVAL;
  		goto errout;
  	}
  
  	/*
  	 * If buf is string, give it terminal '\0' to make our life
  	 * easier. If buf is not string, that '\0' is out of space
  	 * indicated by read_sz so caller won't even notice it.
  	 */
  	((char *)buf)[read_sz] = '\0';
  
  	if (!p_buf)
  		free(buf);
  	else
  		*p_buf = buf;
  
  	if (p_read_sz)
  		*p_read_sz = read_sz;
  	return 0;
  
  errout:
  	if (file)
  		pclose(file);
  	free(buf);
  	if (p_buf)
  		*p_buf = NULL;
  	if (p_read_sz)
  		*p_read_sz = 0;
  	return err;
  }
  
  static inline void
  force_set_env(const char *var, const char *value)
  {
  	if (value) {
  		setenv(var, value, 1);
  		pr_debug("set env: %s=%s
  ", var, value);
  	} else {
  		unsetenv(var);
  		pr_debug("unset env: %s
  ", var);
  	}
  }
  
  static void
  version_notice(void)
  {
  	pr_err(
  "     \tLLVM 3.7 or newer is required. Which can be found from http://llvm.org
  "
  "     \tYou may want to try git trunk:
  "
  "     \t\tgit clone http://llvm.org/git/llvm.git
  "
  "     \t\t     and
  "
  "     \t\tgit clone http://llvm.org/git/clang.git
  
  "
  "     \tOr fetch the latest clang/llvm 3.7 from pre-built llvm packages for
  "
  "     \tdebian/ubuntu:
  "
  "     \t\thttp://llvm.org/apt
  
  "
  "     \tIf you are using old version of clang, change 'clang-bpf-cmd-template'
  "
  "     \toption in [llvm] section of ~/.perfconfig to:
  
  "
  "     \t  \"$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS \\
  "
  "     \t     -working-directory $WORKING_DIR -c $CLANG_SOURCE \\
  "
  "     \t     -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -\"
  "
  "     \t(Replace /path/to/llc with path to your llc)
  
  "
  );
  }

  static int detect_kbuild_dir(char **kbuild_dir)
  {
  	const char *test_dir = llvm_param.kbuild_dir;
  	const char *prefix_dir = "";
  	const char *suffix_dir = "";
  
  	char *autoconf_path;

  
  	int err;
  
  	if (!test_dir) {

  		/* _UTSNAME_LENGTH is 65 */
  		char release[128];
  
  		err = fetch_kernel_version(NULL, release,
  					   sizeof(release));
  		if (err)

  			return -EINVAL;

  		test_dir = release;

  		prefix_dir = "/lib/modules/";
  		suffix_dir = "/build";
  	}
  
  	err = asprintf(&autoconf_path, "%s%s%s/include/generated/autoconf.h",
  		       prefix_dir, test_dir, suffix_dir);
  	if (err < 0)
  		return -ENOMEM;
  
  	if (access(autoconf_path, R_OK) == 0) {
  		free(autoconf_path);
  
  		err = asprintf(kbuild_dir, "%s%s%s", prefix_dir, test_dir,
  			       suffix_dir);
  		if (err < 0)
  			return -ENOMEM;
  		return 0;
  	}
  	free(autoconf_path);
  	return -ENOENT;
  }

  static const char *kinc_fetch_script =
  "#!/usr/bin/env sh
  "
  "if ! test -d \"$KBUILD_DIR\"
  "
  "then
  "
  "	exit -1
  "
  "fi
  "
  "if ! test -f \"$KBUILD_DIR/include/generated/autoconf.h\"
  "
  "then
  "
  "	exit -1
  "
  "fi
  "
  "TMPDIR=`mktemp -d`
  "
  "if test -z \"$TMPDIR\"
  "
  "then
  "
  "    exit -1
  "
  "fi
  "
  "cat << EOF > $TMPDIR/Makefile
  "
  "obj-y := dummy.o
  "
  "\\$(obj)/%.o: \\$(src)/%.c
  "
  "\t@echo -n \"\\$(NOSTDINC_FLAGS) \\$(LINUXINCLUDE) \\$(EXTRA_CFLAGS)\"
  "
  "EOF
  "
  "touch $TMPDIR/dummy.c
  "
  "make -s -C $KBUILD_DIR M=$TMPDIR $KBUILD_OPTS dummy.o 2>/dev/null
  "
  "RET=$?
  "
  "rm -rf $TMPDIR
  "
  "exit $RET
  ";

  void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)

  {

  	static char *saved_kbuild_dir;
  	static char *saved_kbuild_include_opts;

  	int err;

  	if (!kbuild_dir || !kbuild_include_opts)

  		return;
  
  	*kbuild_dir = NULL;

  	*kbuild_include_opts = NULL;

  	if (saved_kbuild_dir && saved_kbuild_include_opts &&
  	    !IS_ERR(saved_kbuild_dir) && !IS_ERR(saved_kbuild_include_opts)) {
  		*kbuild_dir = strdup(saved_kbuild_dir);
  		*kbuild_include_opts = strdup(saved_kbuild_include_opts);
  
  		if (*kbuild_dir && *kbuild_include_opts)
  			return;
  
  		zfree(kbuild_dir);
  		zfree(kbuild_include_opts);
  		/*
  		 * Don't fall through: it may breaks saved_kbuild_dir and
  		 * saved_kbuild_include_opts if detect them again when
  		 * memory is low.
  		 */
  		return;
  	}

  	if (llvm_param.kbuild_dir && !llvm_param.kbuild_dir[0]) {
  		pr_debug("[llvm.kbuild-dir] is set to \"\" deliberately.
  ");
  		pr_debug("Skip kbuild options detection.
  ");

  		goto errout;

  	}
  
  	err = detect_kbuild_dir(kbuild_dir);
  	if (err) {
  		pr_warning(
  "WARNING:\tunable to get correct kernel building directory.
  "
  "Hint:\tSet correct kbuild directory using 'kbuild-dir' option in [llvm]
  "
  "     \tsection of ~/.perfconfig or set it to \"\" to suppress kbuild
  "
  "     \tdetection.
  
  ");

  		goto errout;

  	}

  
  	pr_debug("Kernel build dir is set to %s
  ", *kbuild_dir);
  	force_set_env("KBUILD_DIR", *kbuild_dir);
  	force_set_env("KBUILD_OPTS", llvm_param.kbuild_opts);
  	err = read_from_pipe(kinc_fetch_script,
  			     (void **)kbuild_include_opts,
  			     NULL);
  	if (err) {
  		pr_warning(
  "WARNING:\tunable to get kernel include directories from '%s'
  "
  "Hint:\tTry set clang include options using 'clang-bpf-cmd-template'
  "
  "     \toption in [llvm] section of ~/.perfconfig and set 'kbuild-dir'
  "
  "     \toption in [llvm] to \"\" to suppress this detection.
  
  ",
  			*kbuild_dir);
  
  		free(*kbuild_dir);
  		*kbuild_dir = NULL;

  		goto errout;

  	}
  
  	pr_debug("include option is set to %s
  ", *kbuild_include_opts);

  
  	saved_kbuild_dir = strdup(*kbuild_dir);
  	saved_kbuild_include_opts = strdup(*kbuild_include_opts);
  
  	if (!saved_kbuild_dir || !saved_kbuild_include_opts) {
  		zfree(&saved_kbuild_dir);
  		zfree(&saved_kbuild_include_opts);
  	}
  	return;
  errout:
  	saved_kbuild_dir = ERR_PTR(-EINVAL);
  	saved_kbuild_include_opts = ERR_PTR(-EINVAL);

  }

  int llvm__get_nr_cpus(void)
  {
  	static int nr_cpus_avail = 0;
  	char serr[STRERR_BUFSIZE];
  
  	if (nr_cpus_avail > 0)
  		return nr_cpus_avail;
  
  	nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
  	if (nr_cpus_avail <= 0) {
  		pr_err(
  "WARNING:\tunable to get available CPUs in this system: %s
  "
  "        \tUse 128 instead.
  ", str_error_r(errno, serr, sizeof(serr)));
  		nr_cpus_avail = 128;
  	}
  	return nr_cpus_avail;
  }
  
  void llvm__dump_obj(const char *path, void *obj_buf, size_t size)

  {
  	char *obj_path = strdup(path);
  	FILE *fp;
  	char *p;
  
  	if (!obj_path) {

  		pr_warning("WARNING: Not enough memory, skip object dumping
  ");

  		return;
  	}
  
  	p = strrchr(obj_path, '.');
  	if (!p || (strcmp(p, ".c") != 0)) {
  		pr_warning("WARNING: invalid llvm source path: '%s', skip object dumping
  ",
  			   obj_path);
  		goto out;
  	}
  
  	p[1] = 'o';
  	fp = fopen(obj_path, "wb");
  	if (!fp) {
  		pr_warning("WARNING: failed to open '%s': %s, skip object dumping
  ",
  			   obj_path, strerror(errno));
  		goto out;
  	}
  
  	pr_info("LLVM: dumping %s
  ", obj_path);
  	if (fwrite(obj_buf, size, 1, fp) != 1)
  		pr_warning("WARNING: failed to write to file '%s': %s, skip object dumping
  ",
  			   obj_path, strerror(errno));
  	fclose(fp);
  out:
  	free(obj_path);
  }

  int llvm__compile_bpf(const char *path, void **p_obj_buf,
  		      size_t *p_obj_buf_sz)
  {

  	size_t obj_buf_sz;
  	void *obj_buf = NULL;

  	int err, nr_cpus_avail;

  	unsigned int kernel_version;

  	char linux_version_code_str[64];

  	const char *clang_opt = llvm_param.clang_opt;

  	char clang_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
  	char serr[STRERR_BUFSIZE];

  	char *kbuild_dir = NULL, *kbuild_include_opts = NULL;

  	const char *template = llvm_param.clang_bpf_cmd_template;

  	if (path[0] != '-' && realpath(path, abspath) == NULL) {
  		err = errno;
  		pr_err("ERROR: problems with path %s: %s
  ",

  		       path, str_error_r(err, serr, sizeof(serr)));

  		return -err;
  	}

  	if (!template)
  		template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;
  
  	err = search_program(llvm_param.clang_path,
  			     "clang", clang_path);
  	if (err) {
  		pr_err(
  "ERROR:\tunable to find clang.
  "
  "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH
  "
  "     \tand 'clang-path' option in [llvm] section of ~/.perfconfig.
  ");
  		version_notice();
  		return -ENOENT;
  	}

  	/*
  	 * This is an optional work. Even it fail we can continue our
  	 * work. Needn't to check error return.
  	 */

  	llvm__get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);

  	nr_cpus_avail = llvm__get_nr_cpus();

  	snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
  		 nr_cpus_avail);

  	if (fetch_kernel_version(&kernel_version, NULL, 0))
  		kernel_version = 0;

  	snprintf(linux_version_code_str, sizeof(linux_version_code_str),

  		 "0x%x", kernel_version);

  	force_set_env("NR_CPUS", nr_cpus_avail_str);

  	force_set_env("LINUX_VERSION_CODE", linux_version_code_str);

  	force_set_env("CLANG_EXEC", clang_path);
  	force_set_env("CLANG_OPTIONS", clang_opt);

  	force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);

  	force_set_env("WORKING_DIR", kbuild_dir ? : ".");

  
  	/*
  	 * Since we may reset clang's working dir, path of source file
  	 * should be transferred into absolute path, except we want
  	 * stdin to be source file (testing).
  	 */
  	force_set_env("CLANG_SOURCE",

  		      (path[0] == '-') ? path : abspath);

  
  	pr_debug("llvm compiling command template: %s
  ", template);
  	err = read_from_pipe(template, &obj_buf, &obj_buf_sz);
  	if (err) {
  		pr_err("ERROR:\tunable to compile %s
  ", path);
  		pr_err("Hint:\tCheck error message shown above.
  ");
  		pr_err("Hint:\tYou can also pre-compile it into .o using:
  ");
  		pr_err("     \t\tclang -target bpf -O2 -c %s
  ", path);
  		pr_err("     \twith proper -I and -D options.
  ");
  		goto errout;
  	}

  	free(kbuild_dir);

  	free(kbuild_include_opts);

  	if (!p_obj_buf)
  		free(obj_buf);
  	else
  		*p_obj_buf = obj_buf;
  
  	if (p_obj_buf_sz)
  		*p_obj_buf_sz = obj_buf_sz;
  	return 0;
  errout:

  	free(kbuild_dir);

  	free(kbuild_include_opts);

  	free(obj_buf);
  	if (p_obj_buf)
  		*p_obj_buf = NULL;
  	if (p_obj_buf_sz)
  		*p_obj_buf_sz = 0;
  	return err;
  }

  
  int llvm__search_clang(void)
  {
  	char clang_path[PATH_MAX];
  
  	return search_program(llvm_param.clang_path, "clang", clang_path);
  }